Process for making elastomer/non-elastomer staple fibre yarns



United States Patent U.S. Cl. 57--157 9 Claims ABSTRACT OF THE DISCLOSURE A composite yarn comprising potentially shrinkable elastomeric and non-elastomeric staple fibres is produced by forming a composite roving of a continuous filament elastomer and a sliver of non-elastomeric staple fibres at the front rollers of a roving machine, the elastomeric filaments are then stretch broken on a conventional cotton or worsted spinning machine.

The present invention relates to elastomer/non-elastomer staple fibre yarns and is especially concerned with novel methods for the manufacture thereof.

It has been proposed in British patent specification Nos. 893,758 and 997,291 to manufacture composite yarns composed of mixtures of elastomeric and non-elastomeric staple fibres in proportions varying from 50% to less than of the elastomeric fibres. It has also been proposed in British patent specification No. 996,874 that for some end uses the elastomeric fibres should be shrinkable and the non-elastomeric fibres should be dimensionally relatively stable and that the elastomeric fibres should constitute from 5% to 80% of the yarn.

In the manufacture of yarns as aforementioned staple fibres of the two types are first blended or mixed together into a sliver or roping which is then further processed and spun into a yarn. During the further processing it may be arranged that the elastomeric staple fibres are stretched, as disclosed in British patent specification Nos. 893,758 and 997,291.

We have now found that composite yarns containing elastomeric and non-elastomeric staple fibres can conveniently be produced by first producing a composite roving of non-elastomeric staple fibres and elastomeric continuous filaments, then subjecting the composite roving to a drafting process in which the draft is sufficient to break the elastomeric continuous filaments into staple length fibres, i.e., the elastomeric filaments are stretchbroken, and finally forming the roving into a yarn. The elastomeric staple fibres produced in the stretch-breaking operation have a length of between 7.5 and 43 cms.

Accordingly therefore the present invention provides a process for the manufacture of a composite yarn comprising elastomeric and non-elastomeric staple fibres wherein a composite roving is formed from non-elastomeric staple fibres and an elastomeric material in continuous filament form, which roving is subjected to a stretch-breaking process to break the elastomeric material in continuous filament form into staple fibres and the composite staple fibre roving then spun into a yarn.

The invention also includes yarns made according to the process of this invention.

Preferably the composite roving is formed by the introduction of the elastomer in continuous filament form into a non-elastomeric roving at the front rollers of a roving machine and the elastomeric filaments then stretch broken on a conventional cotton or worsted spinning machine.

It is also preferred that the elastomeric filaments used in the process of this invention should be potentially shrinkable, the yarn obtained after a shrinking treatment having a desirably increased elasticity compared with corresponding core spun yarns.

In the context of the present invention elastomeric fibres are defined as exhibiting a degree of reversible extensibility of over (by reversible is meant that on being released the extended yarn contracts until at least 80% of the extension has gone); and the non-elastomeric fibres defined as possessing a degree of extensibility at break (along the filamentary axis) of less than 50% The term potentially shrinkable as applied to the elastomeric filaments employed in this invention refers to those filaments which, having been stretch-broken in the presence of other non-elastomeric fibres, on being heated in, for example, boiling water or steam in a relaxed condition, i.e., under negligible tension, shrink or contract along their filamentary axis by at least 25% of their original length. The non-elastomeric fibres, in contrast, should be dimensionally relatively stable, by which term is meant that when heated under the same conditions the fibres shrink along their filamentary axis by less than 15%.

As an example of a suitable synthetic elastomer for use in the preferred process of this invention there may be mentioned the polyester urethanes derived from a hydroxyl-terminated copolyester of molecular weight greater than 1500, a dihydric alcohol and an aliphatic or cycloaliphatic diisocyanate.

As examples of suitable synthetic non-elastomers these may be mentioned polyesters, such as polyethylene terephthalate; polyamides, such as polyhexamethylene adipamide (66 nylon) and polyepsilon caprolactam (6 nylon) and the linear polyolefins, such as linear polypropylene. There may also be employed as the non-elastomer component glass, cotton and wool for example.

The non-elastomeric fibres may be in a crimped state, which may have been alfected by edge, false-twist or stufier-box crimping processes.

The yarns produced by the present process may be fabricated into fabrics by knitting, weaving and other conventional methods.

The following example is by way of illustration only and is not intended to limit the invention.

EXAMPLE In this example the non-elastomer is a 3 d.p.f. stufi'erbox crimped 66 nylon staple and the elastomer a 70 denier continuous filament polyester urethane yarn as described above having, in the stretch-broken state, a shrinkage in boiling water of 38%.

66 nylon staple fibre sl-ubbing was passed through a Bradford type roving machine in the normal manner and the elastomer introduced to the roving at the front rollers of the roving machine to form a composite roving. Four such composite rovings were doubled at the spinning frame and a draft of 7.3 used, to ensure complete stretchbreaking of the elastomer, to yield a 295 denier (27 wc.) yarn having a 13 t.p.i. Z twist and containing 9.5% by weight of the elastomer. Physical properties of the composite yarn are given in the table below. Physical properties of a core-spun yarn containing 7% of the same elastomer at extension are also included for the purpose of comparison.

Visual examination of the yarn showed that the elastomeric staple fibres were bound within the yarn structure along its length.

The stretch-breaking and shrinking processes cause marked changes in the denier of the elastomeric fibres, thus a 70 denier yarn becomes 36 denier on stretch-breaking and increases to 42 denier on shrinking in boiling water.

What I claim is:

1. A process for the manufacture of a composite yarn comprising elastomeric and non-elastomeric staple fibres wherein a composite roving is formed from non-elastomeric staple fibres and an elastomeric material in continuous filament form, which roving is subjected to a stretch-breaking process to break the elastomeric material in continuous filament form into staple fibres and the composite staple fibre roving then spun into a yarn.

2. A process according to claim 1 wherein the composite roving is formed by the introduction of the elastomer in continuous filament form into a non-elastomeric roving at the front rollers of a roving machine and the elastomeric material in continuous filament form then stretch-broken on a conventional cotton or worsted spinning machine.

3. A process according to claim 1 wherein the elastomeric material is potentially shrinkable.

4. A process according to claim 3 wherein the composite yarn is further subjected to a shrinkage treatment.

5. A process according to claim 3 wherein the clastomeric material is formed from a polyesterurethane derived from a hydroxyl terminated copolyester of molecular weight greater than 1500, a dihydric alcohol and an aliphatic or cycloaliphatic diisocyanate.

6. A process according to claim 1 wherein the nonelastomeric staple fibres are formed from a polyamide, polyester or linear polyolefin.

7. A process according to claim 1 wherein the nonelastomeric staple fibres are formed from cotton or wool.

8. A process according to claim 1 wherein the nonelastomeric fibres are crimped.

9. A process for the manufacture of a composite yarn comprising elastomeric and non-elastomeric staple fibres, said process comprising: forming a composite roving by introducing continuous elastomeric filaments into a slubbing of staple non-elastomeric fibres and subjecting the resulting composite structure to a roving treatment, said elastomeric filaments having a potential heat shrinkage of at least 25% after being stretch-broken and said nonelastomeric fibres having a potential heat shrinkage of less than 15%; stretching the composite roving to break the elastomeric filaments into staple fibres; spinning the resulting composite staple fibre roving into a yarn; and subjecting the yarn to a heat shrinkage treatment to shrink the elastomeric staple fibres.

References Cited UNITED STATES PATENTS 3,199,283 8/1965 Livingston 57 91 XR 3,205,648 9/1965 Lohrke 57 156 XR 3,300,956 1/1967 Phillips 57-97 XR 3,394,538 7/1968 Netf 57 -156 XR 2,044,130 6/1936 Sowter 19 .43 XR 2,160,178 5/1939 Sitzler 19-.56 XR 2,517,946 8/1950 VOH Kohorn 19 .37 XR 3,007,227 11/1961 IVIOlCI 57 3,070,950 1/1963 Thomas 57 -157 3,077,006 2/1963 Ibrahim.

3,353,345 11/1967 Setzer 57 140 DONALD E. WATKINS, Primary Examiner. 

